The thickness of the endometrium should be considered in relation to the corresponding menstrual cycle and the possibility of a menstrual flow. If the menstrual cycle has been regular, the endometrial thickness of 8 mm, which occurs around 10 days after ovulation, may be followed by the onset of menstruation. The thickness of the endometrium before menstruation varies according to the individual. Sometimes it will be thinner before menstruation due to the negative impact of the ovarian endocrine function, and some will be thicker. In general, if the thickness of the endometrium before menstruation is below 7 mm, the corresponding ovarian endocrine function is poor, and consequently the menstrual flow may be low. The thickness of the endometrium before menstruation is an important aspect of ovarian function, and it is possible to have a normal menstrual flow with an endometrial thickness of 8mm.